let n = 5
let time = 0
let stair = n=>{
    let left = n//左树
    let right = n//右树
    if(n>=0){
        stair(left-1)
        stair(right-2)
    }
    if(n==0){
        time += 1
    }
}
stair(n)
console.log(time)
